Preparation and use of phenylstyrene

ABSTRACT

A process for producing phenylstyrene comprises contacting benzene with hydrogen in the presence of a hydroalkylation catalyst under conditions effective to produce a hydroalkylation product comprising cyclohexylbenzene. At least part of the cyclohexylbenzene is then contacted with ethylbenzene in the presence of a transalkylation catalyst under conditions effective to produce a transalkylation product comprising cyclohexylethylbenzene and/or with ethylene in the presence of an alkylation catalyst under conditions effective to produce an alkylation product comprising cyclohexylethylbenzene. At least part of the cyclohexylethylbenzene is then contacted with a dehydrogenation catalyst under conditions effective to produce a dehydrogenation product comprising phenylstyrene.

CROSS-REFERENCE OF RELATED APPLICATIONS

This application is a National Phase Application claiming priority toPCT/US2016/057168, filed Oct. 14, 2016, which claims priority to and thebenefit of U.S. Ser. No. 62/258,165, filed Nov. 20, 2015, and EPapplication 16152671.0, filed Jan. 26, 2016.

FIELD OF THE INVENTION

This invention relates to a process for preparing phenylstyrene, inparticular, the para-isomer of phenylstyrene, 4-vinylbiphenyl, and itsuse in the production of polymers.

BACKGROUND OF THE INVENTION

Styrene is an important precursor to polystyrene and related polymers.It is produced industrially by the dehydrogenation of ethylbenzene.Approximately 25 million tonnes (55 billion pounds) of styrene wereproduced in 2010.

Phenylstyrene, when polymerized alone or with other monomers, has beenshown to produce polymers with attractive properties for a variety ofpotential applications. For example, phenylstyrene has been proposed asa partial replacement for styrene in the production of polymers havingimproved thermal stability (Borodina et al., Petroleum Chemistry, 49(2009), 66) or improved electrical stability (Gustafsson et al., PolymerEngineering and Science, 33 (1993) 549).

Of the various isomers of phenylstyrene, the para-isomer,4-vinylbiphenyl, has been proposed for use in a number of electronicdevices. In one example, poly(4-vinylbiphenyl) is proposed as animproved polymer additive for semiconductor devices (US 2011/0180784),whereas in another example 4-vinylbiphenyl is identified as a monomer(either alone or with a styrene comonomer) for films for use in opticaldevices, such as liquid crystal displays (US 2008/0241428).

However, no economically viable process for the production ofphenylstyrene currently exists and hence there is significant interestin developing a synthesis route for phenylstyrene that would enable itspromising properties to be realized at a commercially acceptable scaleand cost.

SUMMARY OF THE INVENTION

According to the present invention, a heterogeneously catalyzed seriesof reactions has been identified to produce phenylstyrene from benzeneand ethylbenzene (or benzene and ethylene) as feedstocks. The reactionsequence involves hydroalkylation of benzene to producecyclohexylbenzene, followed by conversion of cyclohexylbenzene tocyclohexylethylbenzene either by transalkylation with ethylbenzene oralkylation with ethylene, then dehydrogenation of thecyclohexylethylbenzene to produce phenylstyrene. Alternatively,cyclohexylethylbenzene can be supplied as a feedstock. In such aspects,the reaction sequence involves conversion of cyclohexylethylbenzeneeither by transalkylation with ethylbenzene or alkylation with ethylene,then dehydrogenation of the cyclohexylethylbenzene to producephenylstyrene. The dehydrogenation process can be conducted in twoseparate reaction steps or in a single combined step. A variation ofthis process involves dehydrogenation of the cyclohexylbenzene tobiphenyl followed by ethylation to produce ethylbiphenyl, and thendehydrogenation to produce the desired phenylstyrene. Yet alternatively,biphenyl can be supplied as a feedstock. In such aspects, the reactionsequence involves ethylation of the biphenyl to produce ethylbiphenyl,and then dehydrogenation to produce the desired phenylstyrene.

Thus, in one aspect, the invention resides in a process for producingphenylstyrene, the process comprising:

-   (a1) contacting benzene with hydrogen in the presence of a    hydroalkylation catalyst under conditions effective to produce a    hydroalkylation product comprising cyclohexylbenzene;-   (b1) converting at least part of the cyclohexylbenzene from (a1) to    cyclohexylethylbenzene by contacting the cyclohexylbenzene with    ethylbenzene in the presence of a transalkylation catalyst under    conditions effective to produce a transalkylation product comprising    cyclohexylethylbenzene; and/or contacting the cyclohexylbenzene with    ethylene in the presence of an alkylation catalyst under conditions    effective to produce an alkylation product comprising    cyclohexylethylbenzene; and-   (c1) contacting at least part of the cyclohexylethylbenzene from    (b1) with at least one dehydrogenation catalyst under conditions    effective to produce a dehydrogenation product comprising    phenylstyrene.

In another aspect, the invention resides in a process for producingphenylstyrene, the process comprising:

-   (a2) converting cyclohexylbenzene to cyclohexylethylbenzene by    contacting the cyclohexylbenzene with ethylbenzene in the presence    of a transalkylation catalyst under conditions effective to produce    a transalkylation product comprising cyclohexylethylbenzene; and/or    contacting the cyclohexylbenzene with ethylene in the presence of an    alkylation catalyst under conditions effective to produce an    alkylation product comprising cyclohexylethylbenzene; and-   (b2) contacting at least part of the cyclohexylethylbenzene from    (a2) with at least one dehydrogenation catalyst under conditions    effective to produce a dehydrogenation product comprising    phenylstyrene.

In one embodiment, the contacting (c1) or (b2) to convert thecyclohexylethylbenzene to phenylstyrene is conducted in a single step.

In another embodiment, the contacting (c1) or (b2) comprises:

-   i) contacting at least part of the cyclohexylethylbenzene from (b1)    with a first dehydrogenation catalyst to produce a first    dehydrogenation product comprising ethylbiphenyl; and-   (ii) contacting at least part of the ethylbiphenyl from (i) with a    second dehydrogenation catalyst to produce a second dehydrogenation    product comprising phenylstyrene.

In another aspect, the invention resides in a process for producingphenylstyrene, the process comprising:

-   (a3) contacting benzene with hydrogen in the presence of a    hydroalkylation catalyst under conditions effective to produce a    hydroalkylation product comprising cyclohexylbenzene;-   (b3) contacting at least part of the cyclohexylbenzene from (a2)    with a first dehydrogenation catalyst to produce a first    dehydrogenation product comprising biphenyl;-   (c3) contacting at least part of the biphenyl from (b2) with an    alkylation catalyst and ethylene under conditions effective to    produce an alkylation product comprising ethylbiphenyl; and-   (d3) contacting at least part of the ethylbiphenyl from (c2) with a    second dehydrogenation catalyst to produce a second dehydrogenation    product comprising phenylstyrene.

In another aspect, the invention resides in a process for producingphenylstyrene, the process comprising:

-   (a4) contacting biphenyl with an alkylation catalyst and ethylene    under conditions effective to produce an alkylation product    comprising ethylbiphenyl; and-   (b4) contacting at least part of the ethylbiphenyl from (a4) with a    second dehydrogenation catalyst to produce a second dehydrogenation    product comprising phenylstyrene.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified process flow diagram showing the major reactionand separation steps for a process for producing phenylstyrene frombenzene and ethylbenzene according to one example of the presentinvention.

FIG. 2 is a graph for Example 3 showing the composition of the reactoreffluent against time-on-stream (TOS) at various reactor temperatures inthe alkylation of cyclohexylbenzene (CHB). Conditions: 450-550 psig(3100-3800 kPa-g); 190-250° C.; 1 gmol CHB (initial); andCHB:Ethylene=3.5:1 (molar basis).

FIG. 3 is a graph for Example 4 showing the composition of the reactoreffluent in the alkylation of biphenyl (BP). Conditions: 450-550 psig(3100-3800 kPa-g); 220° C.; 1 gmol BP (initial); BP:Ethylene=3.5:1(molar basis); and 4 h TOS.

FIG. 4 is a graph for Example 6A showing the compositions of thehydrocarbon (HC) feed and reactor effluent in the dehydrogenation of1-cyclohexyl-2-ethylbenzene (2-CHEB). Conditions: WHSV=10 h⁻¹; 100 psig(690 kPa-g); 425° C.; and Hydrogen:HC Feed=2:1 (molar basis).

FIG. 5 is a graph for Example 6B showing the compositions of the HC feedand reactor effluent in the dehydrogenation of 4-ethylcyclohexylbenzene(4-CHEB). Conditions: 100 psig (690 kPa-g); 450° C.; and Hydrogen:HCFeed=2:1 (molar basis).

DETAILED DESCRIPTION OF THE EMBODIMENTS

The present invention provides a sequence of heterogeneously catalyzedreactions for the production of phenylstyrene from the readily availablefeedstocks (i) benzene and (ii) ethylbenzene or ethylene and benzenereacting in situ. The overall sequence route is net positive in hydrogenproduction and hence, in addition to producing phenylstyrene, couldprovide a valuable source of hydrogen for a refinery and/or chemicalplant. Preferably, the sequence of heterogeneously catalyzed reactionsenables the production of phenylstyrene in quantities of greater thanabout 5 kg/hr, preferably greater than about 500 kg/hr, preferablygreater than about 5000 kg/hr, and preferably greater than about 35000kg/hr.

In some embodiments, the novel reaction sequence involves initiallycontacting benzene with hydrogen in the presence of a hydroalkylationcatalyst under conditions so as hydroalkylate the benzene tocyclohexylbenzene. The next reaction stage involves transalkylation ofthe resultant cyclohexylbenzene with ethylbenzene to producecyclohexylethylbenzene. The ethylbenzene may be produced prior to thetransalkylation reaction and fed as ethylbenzene to the relevantreaction zone. Alternately or additionally, benzene and ethylene may befed to the transalkylation reaction zone such that at least part of theethylbenzene is formed in situ. Finally, as an alternative or supplementto transalkylation, ethylene may be fed in a second reaction zone,possibly under different conditions or over a different catalyst, toalkylate the cyclohexylbenzene directly to cyclohexylethylbenzene. Thefinal reaction stage includes the dehydrogenation ofcyclohexylethylbenzene to produce the phenylstyrene product and can beeffected in a single step or in two separate steps. In the latter case,the cyclohexylethylbenzene is dehydrogenated to ethylbiphenyl in a firststep and then the ethylbiphenyl is dehydrogenated to the desiredphenylstyrene product in a second step.

The overall reaction sequence, in which the cyclohexylbenzene istransalkylated with ethylbenzene to produce cyclohexylethylbenzene, maysummarized by the following reaction scheme, in which the floating bondassociated with the ethyl group denotes that the position of the ethylgroup can vary.

Overall, the selectivity toward cyclohexylethylbenzene is 50% or more,preferably 60% or more, preferably 70% or more, preferably 80% or more(moles cyclohexylethylbenzene produced per mole cyclohexylbenzeneconsumed).

The overall reaction sequence, in which cyclohexylbenzene is alkylatedwith ethylene to produce cyclohexylethylbenzene, may be summarized bythe following reaction scheme, again in which the floating bondassociated with the ethyl group denotes that the position of the ethylgroup can vary.

In other embodiments, the novel reaction sequence again includeshydroalkylation of benzene to produce cyclohexylbenzene, but the nextreactive step includes dehydrogenating at least part of thecyclohexylbenzene to produce a first dehydrogenation product comprisingbiphenyl. At least part of the biphenyl is then alkylated with ethyleneto produce an alkylation product comprising ethylbiphenyl. In the finalreactive step, at least part of the resultant ethylbiphenyl from (c2) isdehydrogenated to produce a second dehydrogenation product comprisingphenylstyrene. In this case, the overall reaction sequence may besummarized by the following reaction scheme, again in which the floatingbond associated with the ethyl group denotes that the position of theethyl group can vary.

Hydroalkylation of Benzene to Cyclohexylbenzene

The first step in the present reaction sequence for producingphenylstyrene comprises contacting benzene with hydrogen in the presenceof a hydroalkylation catalyst. The catalyst and conditions are selectedsuch that the benzene is selectively hydrogenated to cyclohexene, whichthen alkylates additional benzene to produce cyclohexylbenzene. Theoverall hydroalkylation reaction may be summarized as follows:

Any commercially available benzene feed can be used in thehydroalkylation step, but in one embodiment the benzene has a puritylevel of at least 99 wt %. Similarly, although the source of hydrogen isnot critical, it is desirable that the hydrogen is at least 99 wt %pure.

In certain embodiments, the total feed to the hydroalkylation stepcontains less than 1000 ppm, such as less than 500 ppm, for example,less than 100 ppm water. In addition, the total feed may contain lessthan 100 ppm, such as less than 30 ppm, for example, less than 3 ppmsulfur and less than 10 ppm, such as less than 1 ppm, for example, lessthan 0.1 ppm nitrogen.

Hydrogen can be supplied to the hydroalkylation step over a wide rangeof values, but the hydrogen supply is desirably arranged such that themolar ratio of hydrogen to benzene in the hydroalkylation feed is fromabout 0.15:1 to about 15:1, such as from about 0.4:1 to about 4:1, forexample, from about 0.4 to about 0.9:1.

In addition to the benzene and hydrogen, a diluent, which issubstantially inert under hydroalkylation conditions, may be supplied tothe hydroalkylation reaction. In certain embodiments, the diluent is ahydrocarbon, in which the desired cycloalkylaromatic product, in thiscase cyclohexylbenzene, is soluble, such as a straight chain paraffinichydrocarbon, a branched chain paraffinic hydrocarbon, and/or a cyclicparaffinic hydrocarbon. Examples of suitable diluents are decane andcyclohexane. Cyclohexane is a particularly attractive diluent since itis a by-product of the hydroalkylation reaction.

Although the amount of diluent is not narrowly defined, advantageouslythe diluent is added in an amount such that the weight ratio of thediluent to the aromatic compound is at least 1:100; for example, atleast 1:10, but no more than 10:1, for example, no more than 4:1.

The hydroalkylation reaction can be conducted in a wide range of reactorconfigurations including fixed bed, slurry reactors, and/or catalyticdistillation towers. In addition, the hydroalkylation reaction can beconducted in a single reaction zone or in a plurality of reaction zones,in which at least the hydrogen is introduced to the reaction in stages.Suitable reaction temperatures are from about 100° C. to about 400° C.,such as from about 125° C. to about 250° C., while suitable reactionpressures are from about 100 kPa to about 7,000 kPa, such as from about500 kPa to about 5,000 kPa.

The catalyst employed in the hydroalkylation reaction is typically abifunctional catalyst comprising a hydrogenation component and a solidacid alkylation component, typically a molecular sieve. The catalyst mayalso include a binder such as clay, alumina, silica and/or metal oxides.The latter may be either naturally occurring or in the form ofgelatinous precipitates or gels, including mixtures of silica and metaloxides. Naturally occurring clays, which can be used as a binder,include those of the montmorillonite and kaolin families, which familiesinclude the subbentonites and the kaolins commonly known as Dixie,McNamee, Georgia, and Florida clays or others in which the main mineralconstituent is halloysite, kaolinite, dickite, nacrite, or anauxite.Such clays can be used in the raw state as originally mined or initiallysubjected to calcination, acid treatment, or chemical modification.Suitable metal oxide binders include silica, alumina, zirconia, titania,silica-alumina, silica-magnesia, silica-zirconia, silica-thoria,silica-beryllia, silica-titania, as well as ternary compositions such assilica-alumina-thoria, silica-alumina-zirconia, silica-alumina-magnesiaand silica-magnesia-zirconia.

Any known hydrogenation metal or compound thereof can be employed as thehydrogenation component of the hydroalkylation catalyst, althoughsuitable metals include palladium, ruthenium, nickel, zinc, tin, cobalt,silver, gold, platinum, and compounds and mixtures thereof, withpalladium being particularly advantageous. In certain embodiments, theamount of hydrogenation metal present in the catalyst is between about0.05 and about 10 wt %, such as between about 0.1 and about 5 wt %, ofthe catalyst.

In one embodiment, the solid acid alkylation component comprises a largepore molecular sieve having a Constraint Index (as defined in U.S. Pat.No. 4,016,218) less than 2. Suitable large pore molecular sieves includezeolite beta, zeolite Y, Ultrastable Y (USY), Dealuminized Y (Deal Y),mordenite, ZSM-3, ZSM-4, ZSM-18, and ZSM-20. Zeolite ZSM-4 is describedin U.S. Pat. No. 4,021,447. Zeolite ZSM-20 is described in U.S. Pat. No.3,972,983. Zeolite Beta is described in U.S. Pat. No. 3,308,069, and Re.No. 28,341. Low sodium Ultrastable Y molecular sieve (USY) is describedin U.S. Pat. No. 3,293,192 and U.S. Pat. No. 3,449,070. Dealuminized Yzeolite (Deal Y) may be prepared by the method found in U.S. Pat. No.3,442,795. Zeolite UHP-Y is described in U.S. Pat. No. 4,401,556.Mordenite is a naturally occurring material, but is also available insynthetic forms, such as TEA-mordenite (i.e., synthetic mordeniteprepared from a reaction mixture comprising a tetraethylammoniumdirecting agent). TEA-mordenite is disclosed in U.S. Pat. No. 3,766,093and U.S. Pat. No. 3,894,104. Preferred large pore molecular sieves foruse as the solid acid alkylation component of the hydroalkylationcatalyst comprise molecular sieves of the BEA and FAU structure type.

In another, more preferred embodiment, the solid acid alkylationcomponent comprises a molecular sieve of the MCM-22 family. The term“MCM-22 family material” (or “material of the MCM-22 family” or“molecular sieve of the MCM-22 family”), as used herein, includes one ormore of:

-   -   molecular sieves made from a common first degree crystalline        building block unit cell, which unit cell has the MWW framework        topology. (A unit cell is a spatial arrangement of atoms which        if tiled in three-dimensional space describes the crystal        structure. Such crystal structures are discussed in the “Atlas        of Zeolite Framework Types”, Fifth edition, 2001, the entire        content of which is incorporated herein by reference);    -   molecular sieves made from a common second degree building        block, being a 2-dimensional tiling of such MWW framework        topology unit cells, forming a monolayer of one unit cell        thickness, preferably one c-unit cell thickness;    -   molecular sieves made from common second degree building blocks,        being layers of one or more than one unit cell thickness,        wherein the layer of more than one unit cell thickness is made        from stacking, packing, or binding at least two monolayers of        one unit cell thickness. The stacking of such second degree        building blocks can be in a regular fashion, an irregular        fashion, a random fashion, or any combination thereof; and    -   molecular sieves made by any regular or random 2-dimensional or        3-dimensional combination of unit cells having the MWW framework        topology.

Molecular sieves of the MCM-22 family generally have an X-raydiffraction pattern including d-spacing maxima at 12.4±0.25, 6.9±0.15,3.57±0.07, and 3.42±0.07 Angstrom. The X-ray diffraction data used tocharacterize the material are obtained by standard techniques using theK-alpha doublet of copper as the incident radiation and a diffractometerequipped with a scintillation counter and associated computer as thecollection system. Molecular sieves of the MCM-22 family include MCM-22(described in U.S. Pat. No. 4,954,325), PSH-3 (described in U.S. Pat.No. 4,439,409), SSZ-25 (described in U.S. Pat. No. 4,826,667), ERB-1(described in EP 0 293 032), ITQ-1 (described in U.S. Pat. No.6,077,498), and ITQ-2 (described in WO 97/17290), MCM-36 (described inU.S. Pat. No. 5,250,277), MCM-49 (described in U.S. Pat. No. 5,236,575),MCM-56 (described in U.S. Pat. No. 5,362,697), and mixtures of two ormore thereof. Related zeolites to be included in the MCM-22 family areUZM-8 (described in U.S. Pat. No. 6,756,030) and UZM-8HS (described inU.S. Pat. No. 7,713,513), both of which are also suitable for use as themolecular sieve of the MCM-22 family.

Although the hydroalkylation reaction, especially using an MCM-22 familyzeolite catalyst, is highly selective towards cyclohexylbenzene, theeffluent from the hydroalkylation reaction will inevitably contain somedicyclohexylbenzene by-product. Depending on the amount of thisdicyclohexylbenzene, it may be desirable to either (a) transalkylate thedicyclohexylbenzene with additional benzene or (b) dealkylate thedicyclohexylbenzene to maximize the production of the desiredmonoalkylated species.

Transalkylation with additional benzene may be conducted in atransalkylation reactor, separate from the hydroalkylation reactor, overa suitable transalkylation catalyst, such as a molecular sieve of theMCM-22 family, zeolite beta, MCM-68 (see U.S. Pat. No. 6,014,018),zeolite Y, and/or mordenite. The transalkylation reaction is desirablyconducted under at least partial liquid phase conditions, which suitablyinclude a temperature of about 100 to about 300° C., a pressure of about800 to about 3500 kPa, a weight hourly space velocity of about 1 toabout 10 hr⁻¹ on total feed, and a benzene/dicyclohexylbenzene weightratio of about 1:1 to about 5:1.

Dealkylation or cracking may also be affected in a reactor separate fromthe hydroalkylation reactor, such as a reactive distillation unit, at atemperature of about 150° C. to about 500° C. and a pressure of 15 to500 psig (200 to 3550 kPa) over an acid catalyst such as analuminosilicate, an aluminophosphate, a silicoaluminphosphate, amorphoussilica-alumina, an acidic clay, a mixed metal oxide, such asWO_(x)/ZrO₂, phosphoric acid, sulfated zirconia, and mixtures thereof.Desirably, the acid catalyst includes at least one aluminosilicate,aluminophosphate, or silicoaluminphosphate of the FAU, AEL, AFI, and MWWfamily. Unlike transalkylation, dealkylation can be conducted in theabsence of added benzene, although it may be desirable to add benzene tothe dealkylation reaction to reduce coke formation. In this case, theweight ratio of benzene to poly-alkylated aromatic compounds in the feedto the dealkylation reaction is desirably from 0 to about 0.9, such asfrom about 0.01 to about 0.5. Similarly, although the dealkylationreaction can be conducted in the absence of added hydrogen, hydrogen isadvantageously introduced into the dealkylation reactor to assist incoke reduction. Suitable hydrogen addition rates are such that the molarratio of hydrogen to poly-alkylated aromatic compound in the total feedto the dealkylation reactor is from about 0.01 to about 10.

Another significant by-product of the hydroalkylation reaction iscyclohexane. Although a C₆-rich stream comprising cyclohexane andunreacted benzene can be readily removed from the hydroalkylationreaction effluent by distillation, owing to the similarity in theboiling points of benzene and cyclohexane, the C₆-rich stream isdifficult to further separate by simple distillation. However, some orall of the C₆-rich stream can be recycled to the hydroalkylation reactorto provide not only part of the benzene feed, but also part of thediluents mentioned above.

In some cases, it may be desirable to supply some of the C₆-rich streamto a dehydrogenation reaction zone, where the C₆-rich stream iscontacted with a dehydrogenation catalyst under dehydrogenationconditions sufficient to convert at least part of the cyclohexane in theC₆-rich stream portion to benzene, which again can be recycled to thehydroalkylation reaction. The dehydrogenation catalyst may comprise (a)a support, (b) a hydrogenation-dehydrogenation component, and (c) aninorganic promoter. In certain embodiments, the support (a) is selectedfrom the group consisting of silica, a silicate, an aluminosilicate,zirconia, and carbon nanotubes, and preferably comprises silica.Suitable hydrogenation-dehydrogenation components (b) comprise at leastone metal selected from Groups 6 to 10 of the Periodic Table ofElements, such as platinum, palladium, and compounds and mixturesthereof. Desirably, the hydrogenation-dehydrogenation component ispresent in an amount from about 0.1 to about 10 wt % of the catalyst. Asuitable inorganic promoter (c) comprises at least one metal or compoundthereof selected from Group 1 of the Periodic Table of Elements, such asa potassium compound. The promoter may be present in an amount fromabout 0.1 to about 5 wt % of the catalyst. Suitable dehydrogenationconditions include a temperature of about 250° C. to about 500° C., apressure of about atmospheric to about 500 psig (100 to 3550 kPa), aweight hourly space velocity of about 0.2 to about 50 hr⁻¹, and ahydrogen to hydrocarbon feed molar ratio of about 0 to about 20.

The cyclohexylbenzene product from the hydroalkylation reaction and anydownstream reaction to remove the impurities discussed herein isseparated from the reaction effluent(s) by conventional means and is fedto the next stage in the reaction sequence.

Conversion of Cyclohexylbenzene to Phenylstyrene ViaCyclohexylethylbenzene

In certain embodiments, the present reaction sequence for producingphenylstyrene proceeds via conversion of the cyclohexylbenzene generatedin the benzene hydroalkylation stage to cyclohexylethylbenzene, followedby dehydrogenation of the cyclohexylethylbenzene.

In one such embodiment, the second reaction stage in the present processcomprises transalkylation of the cyclohexylbenzene generated in thehydroalkylation step with ethylbenzene to produce a mixture ofcyclohexylethylbenzene isomers in which the ethyl group is located atthe 2-, 3-, and 4-positions on the benzene ring (2-, 3-, and 4-isomers).The ethylbenzene required for transalkylation reaction can be providedas a separate feedstock to the transalkylation reaction. Alternately oradditionally, benzene and ethylene may be fed to the transalkylationreaction zone such that at least part of the ethylbenzene is formed insitu. Under this embodiment, cyclohexylbenzene can also be directlyalkylated by ethylene to form the desired cyclohexylethylbenzeneproduct.

The transalkylation reaction can be conducted over a wide range ofconditions but in most embodiments is effected at a temperature fromabout 50° C. to about 400° C., or about 100° C. to about 400° C., suchas about 75° C. to about 250° C., such as from about 100° C. to about200° C., such as from about 125° C. to 185° C., for example, 125° C. to175° C. and a pressure from about 100 to about 10,000 kPa-absolute, suchas from about 100 to about 3550 kPa-absolute, such as from about 1000 toabout 1500 kPa-absolute. The reaction may be conducted in the presenceof a solid acid transalkylation catalyst, such as a molecular sieve and,in particular, a molecular sieve having a large pore molecular sievehaving a Constraint Index (as defined in U.S. Pat. No. 4,016,218) lessthan 2 Suitable large pore molecular sieves include zeolite beta,zeolite Y, Ultrastable Y (USY), Dealuminized Y (Deal Y), mordenite,ZSM-3, ZSM-4, ZSM-18, ZSM-20, and mixtures thereof. Other suitablemolecular sieves include molecular sieves of the MCM-22 family,including MCM-22 (described in U.S. Pat. No. 4,954,325), PSH-3(described in U.S. Pat. No. 4,439,409), SSZ-25 (described in U.S. Pat.No. 4,826,667), ERB-1 (described in EP 0 293 032), ITQ-1 (described inU.S. Pat. No. 6,077,498), ITQ-2 (described in WO 97/17290), MCM-36(described in U.S. Pat. No. 5,250,277), MCM-49 (described in U.S. Pat.No. 5,236,575), MCM-56 (described in U.S. Pat. No. 5,362,697), andmixtures thereof. Related zeolites such as UZM-8 (described in U.S. Pat.No. 6,756,030), and UZM-8HS (described in U.S. Pat. No. 7,713,513) mayalso be used as the or part of the transalkylation catalyst.

Preferred molecular sieves for the transalkylation catalyst comprisethose selected from the group consisting of BEA, FAU, MOR, MFI, MWWframework type molecular sieves, and mixtures thereof.

In some embodiments, the hydroalkylation reaction and the transalkyationreaction can be conducted in the same reaction zone in the presence of asingle catalyst having both alkylation and hydrogenation activity orover a combination of a hydroalkylation catalyst and a transalkylationcatalyst arranged either as a single mixed bed or as multiple beds instacked formation. In these embodiments, hydroalkylation betweenethylbenzene and benzene can occur to directly producecyclohexylethylbenzene, or ethylcyclohexylbenzene.

As mentioned above, the product of the transalkylation reaction willcomprise a mixture of all the isomers of cyclohexylethylbenzene.However, some applications require specific phenylstyrene isomers (often4-vinylbiphenyl is desired). For this purpose, the present process canbe readily adapted to produce this specific isomer of phenylstyrene byisolating, for example, 1-cyclohexyl-4-ethylbenzene, via separation byboiling or melting point (distillation and/or crystallization) and thenrecycling the undesired isomer(s) to the transalkylation reactor wheresubstitution of the aromatic ring can occur with ethylbenzene to producethe desired cyclohexylethylbenzene isomer from the undesiredcyclohexylethylbenzene isomer. This process is general for producing anyisomer or combination of isomers of phenylstyrene, given the ability toseparate the corresponding cyclohexylethylbenzene (CHEB) isomers. Inthis scheme, the transalkylation reaction is used for both netalkylation of cyclohexylbenzene and net isomerization of undesiredcyclohexylethylbenzenes.

Preferably, the transalkyation reaction is particularly useful in theformation of the 4-isomer of CHEB and, ultimately, 4-vinylbiphenyl. Forexample, the transalklation reaction product typically comprises amixture of CHEB isomers having a ratio of 3- to 4-isomers of about 2:1and having little to no amount of 2-isomer (e.g., <2 wt %). Preferably,the transalkylation product comprises a mixture of CHEB isomerscomprising less than about 2 wt %, or less than about 1 wt %, of the2-isomer, greater than about 20 wt %, or greater than about 30 wt %, ofthe 4-isomer, and greater than about 40 wt %, or greater than 50 wt %,of the 3-isomer. Additionally or alternatively, the transalkylationproduct may comprise a mixture of CHEB isomers comprising less thanabout 40 wt %, or less than about 30 wt %, of the 4-isomer, and lessthan about 70 wt %, or less than about 60 wt %, of the 3-isomer.

In addition to cyclohexylethylbenzene, the transalkylation reactioneffluent also contains co-produced benzene, as well as residualcyclohexylbenzene and ethylbenzene. The co-produced benzene can berecovered from the effluent and recycled to the hydroalkylation stage,whereas the residual cyclohexylbenzene and ethylbenzene can be removedfor recycle back to the transalkylation step.

Transalkylation can also be used to change the isomer distribution ofthe cyclohexylethylbenzene. Under the scenario where there is one ormore desired product isomers, the undesired cyclohexylethylbenzeneisomer(s) can be separated and recycled to the transalkylation reactor,whereupon transalkylation with ethylbenzene can result in a differentisomer product.

As an alternative or supplement to transalkylation, to add the ethylgroup to the core molecule (cyclohexylbenzene), ethyl alkylation viacontacting the cyclohexylbenzene feed with ethylene under conditionssuitable for alkylation is an option. The cyclohexylbenzene is reactedwith ethylene over a solid acid or zeolite catalyst to producecyclohexylethylbenzene. Conditions suitable for this reaction includetemperatures of 100-500° C., preferably between 175-325° C. at pressuresbetween 100-10000 kPa-absolute, preferably between 2000-5000kPa-absolute. Typically, the feed consists of a monomer (e.g.,cyclohexylbenzene) to ethylene molar ratio of 1-10, more preferably of1-5, and ideally of 1.5-2.5. Preferably, the ethylene can be injected atvarious points along the alkylation reaction zone. In such aspects, theethylene is typically injected at 1, 2, 3, 4, or 5 separate sites alongthe reaction zone. In another embodiment, a Lewis acid catalyst can beused, such as AlCl₃. The preferred alkylation catalyst comprises amolecular sieve of the MWW framework type (as described in thehydroalkylation section—but without metal). In any embodiment, theamount of catalyst is preferably selected such that the ethyleneconsumption is greater than about 80%, preferably greater than about90%, and ideally about 100%. Generally, the corresponding monomer (e.g.,cyclohexylbenzene) conversion varies depending on the monomer toethylene molar ratio. Preferably, the monomer (e.g., cyclohexylbenzene)consumption is greater than about 1%, or greater than about 30%, orgreater than about 50%, or about 100%. Examples of suitable alkylationprocesses can be found in U.S. Pat. Nos. 5,600,048; 3,751,504;7,399,894; and 7,939,700, the entire contents of which are incorporatedherein by reference.

Typically, the ethyl alkylation reaction product comprises a mixture ofCHEB isomers having a ratio of 2- to 3- to 4-isomers of about 1:2:1.Preferably, the ethyl alkylation product comprises a mixture of CHEBisomers comprising greater than about 5 wt %, or greater than about 10wt %, or greater than about 20 wt % of the 2-isomer, greater than about5 wt %, or greater than about 10 wt %, or greater than about 20 wt % ofthe 4-isomer, and greater than about 10 wt %, or greater than 30 wt %,or greater than about 50 wt % of the 3-isomer. Additionally oralternatively, the ethyl alkylation product may comprise a mixture ofCHEB isomers comprising less than about 20 wt %, or less than about 10wt %, of the 2-isomer, less than about 20 wt %, or less than about 10 wt%, of the 4-isomer, and less than about 30 wt %, or less than about 20wt %, of the 3-isomer.

The final reaction stage then comprises dehydrogenation of the desiredcyclohexylethylbenzene isomer(s), for example,1-cyclohexyl-4-ethylbenzene, to the corresponding isomer(s) ofphenylstyrene, for example, 4-vinylbiphenyl.

In one embodiment, the dehydrogenation may be conducted in a single stepin the presence of a dehydrogenation catalyst comprising a metal oroxide form of Fe, K, Cr, Mo, Ce, Zn, Bi, Ca, Co, Cu, Li, Mg, V, W, Zr,Ti, Mn, B, Al, Si, Pt, Pd, Ni, Ru, Re, Sn, Na, or any combinationthereof. Preferably, the dehydrogenation is conducted in the presence ofan inhibitor to prevent polymerization of the dehydrogenation product.The inhibitor is preferably present in an amount of from about 1 ppm toabout 100 ppm. The dehydrogenation may be conducted in the presence of ahydrogen and/or steam co-feed, for example, such that the molar ratio ofH₂/H₂O:hydrocarbon is from 0.5 to 12, such as from 0.5 to 10, or from 1to 4.

A suitable catalyst to effect the desired dehydrogenation comprises aninorganic support comprising 0.05 wt % to 2 wt % of a metal selectedfrom Group 14 of the Periodic Table of Elements; such as tin, and 0.1 wt% to 5 wt % of a metal selected from Groups 6 to 10 of the PeriodicTable of Elements, such as nickel, platinum and/or palladium, the weightpercents being based upon total weight of the first catalyst.Conveniently, the support is selected from the group consisting ofalumina, silica, a silicate, an aluminosilicate, zirconia, titania andcarbon nanotubes, and preferably comprises silica. Suitabledehydrogenation conditions include a temperature of about 250° C. toabout 700° C., such as about 250° C. to about 600° C., or from about390° C. to about 480° C., or from about 350° C. to about 450° C., apressure of about 10 kPa-a to about 21000 kPa-a, such as from about 100kPa to about 7000 kPa, a weight hourly space velocity of about 0.2 hr⁻¹to about 50 hr⁻¹, such as from about 1 hr⁻¹ to about 10 hr⁻¹, and ahydrogen to hydrocarbon feed molar ratio of about 0 to about 20.Preferably, interstage heating may be employed in the dehydrogenationreaction stage. The dehydrogenation may be conducted in the presence ofa hydrogen and/or steam co-feed, for example, such that the molar ratioof H₂/H₂O:hydrocarbon is from 0.5 to 12, such as from 0.5 to 10, or from1 to 4.

In another embodiment, the dehydrogenation proceeds in two steps, namely(i) dehydrogenation of the cyclohexylethylbenzene with a firstdehydrogenation catalyst to produce a first dehydrogenation productcomprising ethylbiphenyl and then (ii) dehydrogenation of at least partof the ethylbiphenyl in the first dehydrogenation product with a seconddehydrogenation catalyst to produce a second dehydrogenation productcomprising phenylstyrene. A suitable first dehydrogenation catalystcomprises an inorganic support comprising 0.05 wt % to 2 wt % of a metalselected from Group 14 of the Periodic Table of Elements; such as tin,and 0.1 wt % to 5 wt % of a metal selected from Groups 6 to 10 of thePeriodic Table of Elements, such as nickel, platinum, and/or palladium,the weight percents being based upon total weight of the first catalyst.Generally, the Group 14 metal is present in the dehydrogenation catalystin an amount of at least 0.05 wt %, at least 0.1 wt %, at least 0.15 wt%, at least 0.2 wt %, at least 0.3 wt %, at least 0.4 wt %, or at least0.5 wt %, or at least 1 wt %, or at least 5 wt % based upon total weightof the dehydrogenation catalyst. In one embodiment, the Group 14 metalis tin. In various embodiments, the Group 14 is present in an amountbetween 0.05 wt % and 5 wt %, or 0.05 wt % and 1 wt %, or 0.05 wt % and0.5 wt % of the catalyst or between 0.1 wt % and 0.4 wt % of thecatalyst or between 0.1 wt % and 0.3 wt %, or between about 0.15 wt %and 0.2 wt % of the dehydrogenation catalyst. Conveniently, the supportis selected from the group consisting of silica, a silicate, analuminosilicate, zirconia, titania, and carbon nanotubes, and preferablycomprises silica. Suitable dehydrogenation conditions include atemperature of about 250° C. to about 700° C., such as about 250° C. toabout 600° C., or from about 390° C. to about 480° C., or from about350° C. to about 450° C., a pressure of about 10 kPa-a to about 21000kPa-a, such as from about 100 kPa to about 7000 kPa, a weight hourlyspace velocity of about 0.2 hr⁻¹ to about 50 hr⁻¹, such as from about 1hr⁻¹ to about 10 hr⁻¹, and a hydrogen to hydrocarbon feed molar ratio ofabout 0 to about 20, such as from 0.5 to 12, or from 0.5 to 10, or from1 to 4. Suitable materials for the second dehydrogenation catalystcomprises an oxide or metal form of Fe, K, Cr, Mo, Ce, Zn, Bi, Ca, Co,Cu, Li, Mg, V, W, Zr, Ti, Mn, B, Al, Si, Pt, Pd, Ni, Ru, Re, Sn, Na, orany combination thereof. Suitable conditions for the seconddehydrogenation step comprise a temperature from 400 to 700° C. and apressure from 100 to 3550 kPa-a. Either or both of the first and seconddehydrogenation steps can be conducted in the presence of a hydrogenand/or steam co-feed, for example, such that the molar ratio ofH₂/H₂O:hydrocarbon is from 0 to 12, such as from 0 to 12, such as from 0to 10, or from 1 to 4.

Irrespective of whether the cyclohexylethylbenzene dehydrogenation isconducted in one or two steps, the dehydrogenation effluent will containco-produced hydrogen and residual cyclohexylethylbenzene in addition tothe desired phenylstyrene product. The co-produced hydrogen can readilybe flashed from the effluent and recycled to, for example, thedehydrogenation stage or the hydroalkylation stage. The residualcyclohexylethylbenzene can then be separated from the phenylstyrene inthe effluent by, for example, distillation, for recycle back to thedehydrogenation stage, while the phenylstyrene is recovered forpurification.

Irrespective of whether the cyclohexylethylbenzene dehydrogenation isconducted in one or two steps, preferably minimal to no isomerizationoccurs during dehydrogenation. For example, dehydrogenation of a mixtureof CHEB isomers comprising less than about 2 wt %, or less than about 1wt %, of the 2-isomer, greater than about 20 wt %, or greater than about30 wt %, of the 4-isomer, and greater than about 40 wt %, or greaterthan 50 wt %, of the 3-isomer typically produces a mixture ofethylbiphenyl isomers comprising less than about 2 wt %, or less thanabout 1 wt %, of the 2-isomer, greater than about 20 wt %, or greaterthan about 30 wt %, of the 4-isomer, and greater than about 40 wt %, orgreater than 50 wt %, of the 3-isomer and/or a mixture of vinylbiphenylisomers comprising less than about 2 wt %, or less than about 1 wt %, ofthe 2-isomer, greater than about 20 wt %, or greater than about 30 wt %,of the 4-isomer. Similarly, dehydrogenation of a mixture of CHEB isomerscomprising greater than about 5 wt %, or greater than about 10 wt %, orgreater than about 20 wt % of the 2-isomer, greater than about 5 wt %,or greater than about 10 wt %, or greater than about 20 wt % of the4-isomer, and greater than about 10 wt %, or greater than 30 wt %, orgreater than about 50 wt % of the 3-isomer typically produces a mixtureof ethylbiphenyl isomers comprising greater than about 5 wt %, orgreater than about 10 wt %, or greater than about 20 wt % of the2-isomer, greater than about 5 wt %, or greater than about 10 wt %, orgreater than about 20 wt % of the 4-isomer, and greater than about 10 wt%, or greater than 30 wt %, or greater than about 50 wt % of the3-isomer and/or a mixture of vinylbiphenyl isomers comprising greaterthan about 5 wt %, or greater than about 10 wt %, or greater than about20 wt % of the 2-isomer, greater than about 5 wt %, or greater thanabout 10 wt %, or greater than about 20 wt % of the 4-isomer, andgreater than about 10 wt %, or greater than 30 wt %, or greater thanabout 50 wt % of the 3-isomer.

Conversion of Cyclohexylbenzene to Phenylstyrene Via Biphenyl orConversion of Biphenyl to Phenylstyrene

In other embodiments, the present reaction sequence for producingphenylstyrene proceeds via dehydrogenation of the cyclohexylbenzenegenerated in the benzene hydroalkylation stage to biphenyl, followed byethylation of the biphenyl to ethylbiphenyl (EBP) and thendehydrogenation of the ethylbiphenyl to phenylstyrene. Alternatively, abiphenyl feedstock may be provided. In such aspects, the reactionsequence proceeds via ethylation of the biphenyl to ethylbiphenyl (EBP)and then dehydrogenation of the ethylbiphenyl to phenylstyrene.

In these embodiments, suitable catalysts and conditions fordehydrogenation of the cyclohexylbenzene to biphenyl are the same asthose described above for dehydrogenation of cyclohexylethylbenzeneisomer(s) to the corresponding isomer(s) of phenylstyrene.

Suitable catalysts and conditions for ethylation of the biphenyl toethylbiphenyl are the same as those described above for the ethylationof cyclohexylbenzene to ethylcyclohexylbenzene. Generally, hightemperatures (e.g., about 250° C. about 350° C.) and a high monomer(biphenyl) to ethylene molar ratio (e.g., 1-10) are useful formaximizing the production of ethylbiphenyl from biphenyl.

Preferably, the ethylation of biphenyl is particularly useful in theformation of the 2-isomer of EBP and, correspondingly, 2-vinylbiphenyl.Preferably, the ethyl alkylation product comprises a mixture of EBPisomers comprising greater than about 20 wt %, or greater than about 40wt %, or greater than about 50 wt %, or greater than about 60 wt % ofthe 2-isomer, less than about 30 wt %, or less than about 15 wt %, ofthe 4-isomer, and less than about 50 wt %, or less than about 25 wt %,of the 3-isomer. Additionally or alternatively, the ethylation productmay comprise a mixture of EBP isomers comprising less than about 80 wt%, or less than about 70 wt %, of the 2-isomer, greater than about 5 wt%, or greater than about 10 wt %, of the 4-isomer, and greater thanabout 10 wt %, or greater than about 20 wt %, of the 3-isomer.

Suitable catalysts and conditions for dehydrogenation of theethylbiphenyl to phenylstyrene are also described above. Preferably, thedehydrogenation of ethylbiphenyl is conducted at high temperature (e.g.,about 500° C. to about 600° C.) and using an H₂O diluent. Particularlyuseful catalysts for the dehydrogenation of ethylbiphenyl tophenylstyrene include Fe based mixed metal oxides, preferably furthercomprising Cr, Mg, or Na. Often, interstage heating may be employed inthe dehydrogenation reaction stage in the dehydrogenation ofethylbiphenyl. Alternatively, the dehydrogenation may be conductedwithout employing interstage heating. The dehydrogenation effluent willgenerally contain residual ethylbiphenyl in addition to the desiredphenylstyrene product. The residual ethylbiphenyl can then be separatedfrom the phenylstyrene in the effluent by, for example, distillation,for recycle back to the dehydrogenation stage, while the phenylstyreneis recovered for purification.

Preferably minimal to no isomerization occurs during dehydrogenation.For example, dehydrogenation of a mixture of ethylbiphenyl isomerscomprising greater than about 20 wt %, or greater than about 40 wt %, orgreater than about 50 wt %, or greater than about 60 wt % of the2-isomer, less than about 30 wt %, or less than about 15 wt %, of the4-isomer, and less than about 50 wt %, or less than about 25 wt %, ofthe 3-isomer typically produces a mixture of vinylbiphenyl isomerscomprising greater than about 20 wt %, or greater than about 40 wt %, orgreater than about 50 wt %, or greater than about 60 wt % of the2-isomer, less than about 30 wt %, or less than about 15 wt %, of the4-isomer, and less than about 50 wt %, or less than about 25 wt %, ofthe 3-isomer.

Referring now to the drawing, a simplified process flow diagram of oneembodiment of the present reaction sequence via ethylcyclhexylbenzene isshown in FIG. 1, in which benzene and hydrogen are supplied via line 11to a hydroalkylation reactor 12, which is operated under conditionseffective to hydroalkylate the benzene to produce cyclohexylbenzene.Effluent from the hydroalkylation reactor 12 comprises unreacted benzeneand, in some cases unreacted hydrogen, in addition to thecyclohexylbenzene and is fed via line 13 to a first separation system14, where the benzene and hydrogen are removed and recycled via line 15back to the hydroalkylation reactor 12.

Cyclohexylbenzene is recovered from the hydroalkylation effluent by thefirst separation system 14 and is fed via line 16 to a transalkylationreactor 17, which also receives an ethylbenzene feed from line 18. Thetransalkylation reactor 17 is operated under conditions effective forthe ethylbenzene to react with the cyclohexylbenzene to produce atransalkylation effluent comprising a mixture of cyclohexylethylbenzeneisomers and benzene in addition to residual ethylbenzene andcyclohexylbenzene. The effluent from the transalkylation reactor 17 iscollected in line 19 and fed to a second separation system 21.

The second separation system 21 comprises a plurality of distillationcolumns, which are operated to separate the transalkylation effluentinto at least the following fractions:

-   (a) a benzene-containing fraction, which is removed via line 22 for    recycle to the hydroalkylation reactor 12;-   (b) an ethylbenzene-containing fraction, which is removed via line    23 for recycle to the transalkylation reactor 17;-   (c) a cyclohexylbenzene-containing fraction, which is removed via    line 24 for recycle to the transalkylation reactor 17; and-   (d) a cyclohexylethylbenzene-containing fraction, which is removed    via line 25 for supply to a dehydrogenation reactor 26.

In some embodiments, the second separation system 21 includes provisionfor separating the cyclohexylethylbenzene isomers into one or moredesired isomers, for example, 1-cyclohexyl-4-ethylbenzene, which areremoved in line 25 and one or more undesired isomers, for example,1-cyclohexyl-2-ethylbenzene and 1-cyclohexyl-3-ethylbenzene, which canbe recycled, for example, via line 24, to the transalkylation reactor17.

The dehydrogenation reactor 26 is operated under conditions todehydrogenate the cyclohexylethylbenzene isomer(s) supplied via line 25to produce a dehydrogenation effluent containing one or morephenylstyrene isomers together with co-produced hydrogen and residualcyclohexylethylbenzene. The dehydrogenation effluent is supplied vialine 27 to a third separation system 28, where the hydrogen is removedvia line 29 for recycle to the hydroalkylation reactor 12 or thedehydrogenation reactor 26 and the residual cyclohexylethylbenzene isremoved via line 31 for recycle to the dehydrogenation reactor 26. Thephenylstyrene is recovered by line 32 and sent to product purification.

The invention will now be more particularly described with reference tothe following non-limiting Examples.

Samples were analyzed on an Agilent 7890 GC equipped with a 5975C MSDdetector and FID. Typical injection size was about 0.5 μl. The columnsused were from Supelco of the Dex type. A Gamma DEX column was joinedtogether with a Beta Dex column to give a total length of 120 m (60 mfor each type). The internal diameter of the columns was 0.25 mm. Thissetup had a purged 2-way splitter that enabled a sample to besimultaneously analyzed on two detectors using a single injection.Additionally, an auxiliary helium pressure of 6 psi was used for thepurged splitter. The system was operated in constant flow mode with aninitial pressure of about 78 psi and column flow of about 3.0 m/minusing helium as carrier gas. The following oven procedure was utilized:

-   -   Initial temperature of 140° C. and pressure of 78 psi, hold for        30 minutes,    -   Ramp 1 at 2° C./min to 180° C., hold for 20 minutes,    -   Ramp 2 at 3° C./min to 220° C., hold for 27 minutes, and    -   Total analysis time of about 1 to 10 minutes.

EXAMPLE 1 Transalkylation of Cyclohexylbenzene

The experiments reported in Example 1 were conducted in a reactorconsisting of a quartz tube of 9 mm in diameter heated by a furnace.Annular N₂ flow on the outside of the quartz reactor allowed forpressure equilibration between the inside and outside of the reactorchannel USY catalyst extrudates were crushed to 20/40 mesh and 2 g ofthe crushed extrudates were loaded into the reactor after being dilutedup to 4 g in crushed quartz. A quartz wool plug was used at the top andbottom of the catalyst bed to keep catalyst in place. The reactorcontained an internal thermocouple in the catalyst bed in a ⅛″thermowell. The reactor was topped off with the same quartz chips.

The catalyst was dried overnight under N₂ at 290° C. An ISCO syringepump was used to introduce the feed to the reactor. The feed was pumpedthrough a vaporizer before being mixed in-line with N₂ at a molar ratioof 0.7 (gas to hydrocarbon liquid). The products exiting the reactorwere condensed, collected, and analyzed off-line by GCMS in accordancewith the above described procedure.

To study the transalkylation of cyclohexylbenzene with ethylbenzene, aliquid feed consisting of 67% ethylbenzene and 33% cyclohexylbenzene wasfed over the USY catalyst in the reactor described above at a pressureof 165 psig (1239 kPa-a) and a temperature of 165° C. The total WHSV was1 hr⁻¹. Under these conditions, a cyclohexylbenzene conversion of 39%was achieved. Table 1 shows the weight percent of each species in thereactor liquid effluent as determined by the analysis proceduredescribed.

TABLE 1 Species Effluent Liquid Wt % Non-aromatic lights 0.4 Benzene 6.1Toluene 1.2 Xylenes 0.5 Ethylbenzene 54.6 Diethylbenzene 2.1Cyclohexylbenzene 20.0 Cyclohexylethylbenzenes 12.1 Other heavies 3.1

As can be seen from Table 1, reasonable yields of cyclohexylethylbenzene(multiple isomers) can be achieved under moderate operating conditionsvia the transalkylation reaction of cyclohexylbenzene and ethylbenzene.Byproducts include light aromatics from cracking or disproportionation,diethylbenzene from ethyl disproportionation and other heavies resultingfrom multiple alkylation reactions. Overall, the selectivity towardcyclohexylethylbenzene is 80% (moles cyclohexylethylbenzene produced permole cyclohexylbenzene consumed).

To study the isomer distribution formed from the transalkylation ofcyclohexylbenzene with ethylbenzene, the transalkylation reaction wasrepeated using the same conditions described above with the exception ofoperating at a slightly higher temperature of 170° C. The weight percentof the CHEB isomers in the reactor liquid effluent were then determinedby the analysis procedure described. Under these conditions, nomeasurable amount of 2-CHEB was observed. Additionally, 3-CHEB waspresent in the effluent at 8.4 wt % and 4-CHEB was present in theeffluent at 4.2 wt %, That is, the observed isomer distribution was aratio of 3-:4-CHEB isomers of 2:1 with negligible to no 2-isomer.

EXAMPLE 2 Synthesis of Alkylation Catalyst

80 parts MCM-49 crystal were combined with 20 parts pseudoboehmitealumina, on a calcined dry weight basis. The MCM-49 and pseudoboehmitealumina dry powder were placed in a muller or a mixer and mixed forabout 10 to 30 minutes. Sufficient water was added to the MCM-49 andalumina during the mixing process to produce an extrudable paste. Theextrudable paste was formed into a 1/20 inch quadralobe extrudate usingan extruder. After extrusion, the 1/20th inch quadralobe extrudate wasdried at a temperature ranging from 250° F. (121° C.) to 325° F. (163°C.). After drying, the dried extrudate was heated to 1000° F. (538° C.)under flowing nitrogen, then ion exchanged with 0.5 to 1 N ammoniumnitrate solution after cooling. The ammonium nitrate exchanged extrudatewas then dried and then calcined in a nitrogen/air mixture to atemperature of 1000° F. (538° C.).

EXAMPLE 3 Alkylation of Cyclohexylbenzene

To study the alkylation of cyclohexylbenzene with ethylene, 0.25 g ofthe alkylation catalyst of Example 2 along with a feed consisting of 1gmol of cyclohexylbenzene (CHB) and 0.29 gmol of ethylene (3.5:1 molarratio of CHB to ethylene) were charged into a 300 ml Parr reactor at apressure of 165 psig (1239 kPa-a). The reactor was then heated to atemperature ranging from 190° C. to 250° C. FIG. 2 shows the weightpercent of each species in the reactor liquid effluent againsttime-on-stream (TOS) in the reactor at three operating temperatures(190° C., 220° C., and 250° C.) as determined by the above describedanalysis procedure. Table 2 shows the ratio of CHEB isomers to lightbyproducts (by weight percent) in the reactor liquid effluent after 1.5h TOS.

TABLE 2 Temperature (° C.) Ratio 190 4.99 220 4.98 250 1.67

As can be seen from FIG. 2 and Table 2, reasonable selectivity towardscyclohexylethylbenzene (CHEB) (multiple isomers) can be achieved undermoderate operating conditions via the alkylation reaction ofcyclohexylbenzene and ethylene. The conversion of CHB could likely beincreased by conducting the reaction in a flow reactor as opposed to abatch reactor. Primary byproducts include light aromatics from crackingor disproportionation. The typical isomer distribution observed over therange of tested temperatures was a ratio of 2-:3-:4-CHEB isomers of1:2:1. For example, at an operating temperature of 250° C. and 3 h TOS,the observed isomer distribution in the effluent was 0.88 wt % 2-CHEB,2.05 wt % 3-CHEB, and 0.97 wt % 4-CHEB. That is, the alkylation reactionpathway of CHB resulted in a different isomer distribution than thetransalkylation reaction pathway (e.g., higher selectivity towards2-CHEB isomers).

EXAMPLE 4 Alkylation of Biphenyl

To study the alkylation of biphenyl with ethylene, 0.25 g of thealkylation catalyst of Example 2 along with a feed consisting of 1 gmolof biphenyl (BP) and 0.29 gmol of ethylene (3.5:1 molar ratio of BP toethylene) were charged into a 300 ml Parr reactor at a pressure rangingfrom 450-550 psig (3100-3800 kPa-g). The reactor was then heated to atemperature of 220° C. The obtained reactor product was dissolved intoluene for analysis. FIG. 3 shows the weight percent of each species inthe reactor product after 4 h TOS determined by the above describedanalysis procedure (after correcting for the presence of toluene).

As can be seen from FIG. 3, reasonable selectivity towards ethylbiphenyl(E B P) (multiple isomers) can be achieved under moderate operatingconditions via the alkylation reaction of biphenyl and ethylene. Theconversion of BP could likely be increased by conducting the reaction ina flow reactor as opposed to a batch reactor. Primary byproducts includeheavies resulting from multiple alkylation reactions. As can also beseen from FIG. 3, the typical isomer distribution observed was a ratioof 2-:3-:4-EBP isomers of 63:23:14. More specifically, the observedisomer distribution in the product was 8.18 wt % 2-EBP, 3 wt % 3-EBP,and 1.86 wt % 4-EBP. That is, the alkylation reaction pathway of BPresulted in high selectivity towards 2-EBP isomers.

EXAMPLE 5 Dehydrogenation of Cyclohexylethylbenzene

The experiments reported in Examples 5 A and B were conducted in flowreactors consisting of stainless steel tubes ¾ in (19 mm) in diameter.Catalyst extrudates were crushed to 20/40 mesh and loaded into thereactor in quantities ranging from 0.25-1 g (to vary correspondingweight based space velocity). A quartz wool plug was used at the top andbottom of the catalyst bed to keep catalyst in place. The reactors wereplaced in heated furnaces to control isothermal reaction temperature.Each reactor contained an internal thermocouple in the catalyst bed. Thereactors were topped off with the same quartz chips.

The catalyst was pre-conditioned in situ by heating under hydrogen undera slow ramp to maximum temperatures of −500° C. An ISCO syringe pump wasused to introduce the feed to the reactor. The feed was pumped through avaporizer before being mixed in line with H₂. The feed was then pumpedthrough the catalyst bed held at the reaction temperature. An Inhibitor(NACLO EC 3355 A) was added (5 ppm) to the reactor to preventpolymerization of product. The products exiting the reactor werecondensed and collected in intervals (approximately one sample per dayper reactor) and analyzed off-line by GCMS in accordance with the abovedescribed procedure.

EXAMPLE 5A Dehydrogenation of 1-Cyclohexyl-2-Ethylbenzene (2-CHEB)

To study the dehydrogenation of 2-CHEB, a feed consisting of 20% 2-CHEBand balance benzene was fed over a Pt/Sn dehydrogenation catalyst onsilica support in the reactor described above at a pressure of 100 psig(690 kPa-g, a temperature of 425° C., a hydrogen to hydrocarbon molarratio of 2, and a total WHSV of 10 h⁻¹. FIG. 4 and Table 3 show theweight percent of each species in the feed and reactor effluent. Theproduct data of FIG. 4 and Table 3 represents the raw data obtained fromthe GC, and the normalized product data represents estimates the actualpercentage of each species in the effluent after accounting for benzeneloss to atmosphere during measurement.

TABLE 3 Species Feed Wt % Product Wt % Normalized Product Wt % Benzene80.0 72.7 80.0 2-CHEB 18.6 3.99 2.93 2-EBP 0.00 18.8 13.8 Other 1.404.48 3.29

As can be seen from FIG. 4 and Table 3, high conversion (>80%) of 2-CHEBand high selectivity (>80%) towards the desired dehydrogenated product,ethylbiphenyl, was obtained. As can also be seen from FIG. 4 and Table3, all obtained ethylbiphenyl exhibited the ethyl group in the 2position (i.e., no isomerization activity was observed).

EXAMPLE 5B Dehydrogenation of 1-Cyclohexyl-4-Ethylbenzene (4-CHEB)

To study the dehydrogenation of 4-CHEB, a feed consisting of 20% 4-CHEB,5% cyclohexane (CH), and balance benzene (bz) was fed over a Pt/Sndehydrogenation catalyst on silica support in the reactor describedabove at a pressure of 100 psig (690 kPa-g, a temperature of 450° C., ahydrogen to hydrocarbon molar ratio of 2, and a total WHSV of 10 h⁻¹.FIG. 5 and Table 4 shows the weight percent of each species in the feedand reactor effluent. The product data of FIG. 5 and Table 4 representsthe raw data obtained from the GC, and the normalized product datarepresents estimates the actual percentage of each species in theeffluent after accounting for benzene loss to atmosphere duringmeasurement.

TABLE 4 Species Feed Wt % Product Wt % Normalized Product Wt % Benzene76.0 71.5 76.3 Cyclohexane 4.93 3.51 3.75 4-CHEB 18.8 2.12 1.70 4-EBP0.250 21.0 16.8 Other 0.00 1.85 1.48

As can be seen from FIG. 5 and Table 4, high conversion (>85%) of 4-CHEBand high selectivity (ca. 80%) towards the desired dehydrogenatedproduct, ethylbiphenyl, was obtained. As can also be seen from FIG. 5and Table 4, all obtained ethylbiphenyl exhibited the ethyl group in the4 position (i.e., no isomerization activity was observed).

All documents described herein are incorporated by reference herein,including any priority documents and/or testing procedures to the extentthey are not inconsistent with this text. As is apparent from theforegoing general description and the specific embodiments, while formsof the invention have been illustrated and described, variousmodifications can be made without departing from the spirit and scope ofthe invention. Accordingly, it is not intended that the invention belimited thereby. Likewise, the term “comprising” is consideredsynonymous with the term “including.” Likewise, whenever a composition,an element or a group of elements is preceded with the transitionalphrase “comprising,” it is understood that we also contemplate the samecomposition or group of elements with transitional phrases “consistingessentially of,” “consisting of,” “selected from the group of consistingof,” or “is” preceding the recitation of the composition, element, orelements and vice versa.

What is claimed is:
 1. A process for producing phenylstyrene, the process comprising: (a1) contacting benzene with hydrogen in the presence of a hydroalkylation catalyst under conditions effective to produce a hydroalkylation product comprising cyclohexylbenzene; (b1) converting at least part of the cyclohexylbenzene from (a1) to cyclohexylethylbenzene by contacting the cyclohexylbenzene with ethylbenzene in the presence of a transalkylation catalyst under conditions effective to produce a transalkylation product comprising cyclohexylethylbenzene; and/or contacting the cyclohexylbenzene with ethylene in the presence of an alkylation catalyst under conditions effective to produce an alkylation product comprising cyclohexylethylbenzene; and (c1) contacting at least part of the cyclohexylethylbenzene from (b1) with at least one dehydrogenation catalyst under conditions effective to produce a dehydrogenation product comprising phenylstyrene.
 2. The process of claim 1, wherein the contacting (a1) is conducted under conditions including a temperature from about 100° C. to about 400° C. and a pressure from about 100 to about 7,000 kPa.
 3. The process of claim 1, wherein the hydroalkylation catalyst comprises an acidic component and a hydrogenation component.
 4. The process of claim 3, wherein the acidic component of the hydroalkylation catalyst comprises a molecular sieve.
 5. The process of claim 4, wherein the molecular sieve comprises a molecular sieve of the MCM-22 family.
 6. The process of claim 3, wherein the hydrogenation component of the hydroalkylation catalyst is selected from the group consisting of palladium, ruthenium, nickel, zinc, tin, cobalt, and compounds and mixtures thereof.
 7. The process of claim 1, wherein a molar ratio of hydrogen to benzene supplied to the contacting (a1) is from about 0.15:1 to about 15:1.
 8. The process of claim 1, wherein the converting (b1) comprises contacting the cyclohexylbenzene with ethylbenzene in the presence of a transalkylation catalyst under conditions including a temperature from about 100° C. to about 400° C. and a pressure from about 100 to about 10,000 kPa-absolute.
 9. The process of claim 8, wherein the transalkylation catalyst comprises a molecular sieve.
 10. The process of claim 8, wherein the transalkylation catalyst comprises a molecular sieve selected from the group consisting of BEA, FAU, MOR, MFI, MWW framework molecular sieves and mixtures thereof.
 11. The process of claim 1, wherein the converting (b1) comprises contacting the cyclohexylbenzene with ethylene in the presence of an alkylation catalyst under conditions including a temperature from about 100° C. to about 500° C. and a pressure from about 100 to about 10,000 kPa-absolute.
 12. The process of claim 11, wherein the alkylation catalyst comprises a molecular sieve.
 13. The process of claim 1, wherein the contacting (c1) to convert the cyclohexylethylbenzene to phenylstyrene is conducted in a single step.
 14. The process of claim 13, wherein the contacting (c1) is conducted in the presence of a dehydrogenation catalyst comprising a metal or oxide form of Fe, K, Cr, Mo, Ce, Zn, Bi, Ca, Co, Cu, Li, Mg, V, W, Zr, Ti, Mn, B, Al, Si, Pt, Pd, Ni, Ru, Re, Sn, Na, or any combination thereof.
 15. The process of claim 13, wherein the contacting (c1) is conducted in the presence of a hydrogen or steam co-feed.
 16. The process of claim 1, wherein the contacting (c1) to convert the cyclohexylethylbenzene to phenylstyrene comprises: (i) contacting at least part of the cyclohexylethylbenzene from (b1) with a first dehydrogenation catalyst to produce a first dehydrogenation product comprising ethylbiphenyl; and (ii) contacting at least part of the ethylbiphenyl from (i) with a second dehydrogenation catalyst to produce a second dehydrogenation product comprising phenylstyrene.
 17. The process of claim 16, wherein the first dehydrogenation catalyst comprises an element or compound thereof from Group 10 of the Periodic Table of the Elements and an element or compound thereof from Group 14 of the Periodic Table.
 18. The process of claim 16, wherein the first dehydrogenation catalyst comprises silica.
 19. The process of claim 17, wherein the second dehydrogenation catalyst comprises an oxide or metal form of Fe, K, Cr, Mo, Ce, Zn, Bi, Ca, Co, Cu, Li, Mg, V, W, Zr, Ti, Mn, B, Al, Si, Pt, Pd, Ni, Ru, Re, Sn, Na, or any combination thereof.
 20. The process of claim 1, and further comprising: (d) separating at least part of the transalkylation product into a first fraction having an increased concentration of at least one isomer of cyclohexylethylbenzene as compared with the transalkylation product and a second fraction having a decreased concentration of at least one isomer of cyclohexylethylbenzene as compared with the transalkylation product; (e) supplying at least part of the first fraction to the contacting (c1); and (d) recycling the second fraction to the contacting (b1).
 21. The process of claim 20, wherein the at least one isomer of cyclohexylethylbenzene comprises 1-cyclohexyl-4-ethylbenzene. 